Humidity changer



Aug- 7, 1953 N. A. PENNINGTON HUMIDITY CHANGER 5 Sheets-Sheet 1 Filed Nov. 6, 1962 R R mm. W N e um 2 m AA DI ,KQ A86 IIL a e N hmmm, :llllllllll': l

7, 1968 N. A. PENNINGTON 3,398,510

HUMIDITY CHANGER Filed NOV. 6, 1962 3 Sheets-Sheet 2 INVENTOR Neal A fzennington Aug. 27, 1968 Filed Nov. 6

N. A. PENNINGTON HUMIDITY CHANGER Fig.10.

5 Sheets-Sheet 5 INVENTOR Neal A.P-enn ngton ATTORN EY United States Patent 3,398,510 HUMIDITY CHANGER Neal A. Pennington, Tucson, Ariz., assignor to Lizenzia A.G., Zug, Switzerland, a corporation of Switzerland Continuation-impart of application Ser. No. 473,509, Dec. 7, 1954. This application Nov. 6, 1962, Ser. No. 235,784

23 Claims. (Cl. 55-163) This invention relates to a humidity changer, primarily intended for use in an air-conditioning apparatus.

This present application is a continuation-in-part of applicants co-pending application Ser. No. 473,509, filed Dec. 7, 1954 and now abandoned, which application was a division of application Ser. No. 234,301, filed June 29, 1951, now Patent No. 2,700,537, dated Jan. 25, 1955, and which latter application in turn was a continuationin-part of application Ser. No. 765,554, filed Aug. 1, 1947, now abandoned.

Outdoor air, when heated in Winter for use indoors, thereby almost always acquires too low a relative humidity, and hence needs to be humidified. Outdoor air, when cooled in summer, and for use indoors, thereby almost always acquires too high a relative humidity, and hence requires to be dehumidified.

It is, therefore, among the objects of the present invention to provide a simple mechanism and method, adapted to perform selectively, at will or under automatic control the two functions of humidifying and dehumidifying the incoming air.

It is another object of the invention to provide a system permitting moisture-exchange between two streams of air, transferring the moisture in one or the other directions at Will or under automatic control, without any rerouting of the two main air-streams.

Still a further object of the invention is to provide a moisture-transferrer composed of asbestos, treated so as to acquire hygroscopic characteristics, and by which the etiiciency of the described structure will be materially increased.

With these and other objects to be hereinafter set forth in view, I have devised the arrangement of parts to be described and more particularly pointed out in the claims appended hereto.

In the accompanying drawings, wherein illustrative embodiments of the invention are shown,

FIG. 1 is a longitudinal vertical central section of one embodiment of the improved apparatus;

FIG. 2 is a transverse vertical section of the apparatus, taken along the line 22 of FIG. 1, looking in the direction of the arrows;

FIG. 3 is a horizontal section of the rotary moisturetransferrer and adjacent parts of the apparatus, taken along the line 33 of FIG. 2, looking in the direction of the arrows;

FIG. 4 is an enlargment of a portion of FIG. 3, to illustrate the means for preventing the leakage of air past the rotary moisture-transferrer in either air-passage, and for preventing the leakage of air from one air-passage to the other at the periphery of said transferrer;

FIG. 5 is a diagrammatic detailed showing of the gearshift for changing the speed of rotation of the heatexchanger and moisture-transferrer, this gear-shaft being merely indicated in FIG. 1;

FIG. 6 is a vertical sectional view similar to FIG. 1, but disclosing a moisture-transferrer having its body or core composed of corrugated asbestos paper;

FIG. 7 is a sectional view, taken substantially on the line 7-7 of FIG. 6, looking in the direction of the arrows;

FIG. 8 is a horizontal sectional view, taken substanice tially on the line 8-8 of FIG. 7, looking in the direction of the arrows;

FIG. 9 is an enlargement of a portion of FIG. 8;

FIG. 10 is a face View of the core or body of the moisture-transferrer of FIG. 6, and

FIG. 11 is an enlargement of a small section of the moisture-transferrer.

Referring to FIG. 1, it will be noted that the main container of the apparatus is shown at 11 and 12 and is an air-inlet leading from outdoors. The centrifugal fan 13 impels this air into a passage 14 and thence through a filter pad 20, and thence through the upper portion of a rotating wheel-like moisture-transferrer 15. In the embodiment shown in FIG. 1, the moisture-transferrer 15 is constructed very similarly to the aluminum Wool pad shown in my Patent No. 2,464,766, but employs a novel means to prevent the leakage of air from one air-passage to the other, and to prevent the leakage of air past the periphery of the moisture-transferrer.

In FIG. 2 the rim 16, ribs 17, and hub 18 of the moisture-transferrer are of substantially the same width in an axial direction. Each of the sectors between successive ribs is fully and rigidly, but loosely, stulfed with some airpervious, liquid-absorbing, non-heat-conducting packing 19, which may be excelsior or similar filamentous material, or it may be corrugated asbestos paper or the like, with the corrugations extending axially. This arrangement is disclosed in the structure of FIGS. 6 to 11 inclu- SlVfi.

In order to impart hygroscopic characteristics to the filling or packing of the moisture-transferrer, the packing, and particularly in the case of an asbestos material, should be impregnated with some appropriate solution of an hygroscopic liquid or salt such as disclosed in my Patent No. 2,700,537.

The moisture-transferrer 15 rotates clockwise as viewed in FIG. 2. It has two alternative speeds of rotation, as will be later explained. That sectoral portion of the incoming air first treated by this moisture-transferrer, passes therefrom into the by-pass 23, and thence into the outgoing air-stream, for purpose to be explained. If the damper shown at 24 is closed and the damper 25 is opened, this air, instead of being discarded, will pass with the rest of the incoming stream. If there be no damper 25, the damper 24 being closed, all the incoming air will go past the by-pass. In any event, the mainstream of incoming air continues on in the passage 26, until it encounters the heat-transferrer 27, rotating at a speed of approximately 30 r.p.m.

The heat-transferrer 27 may be of the sort composed of the aluminum wool pad, described in my Patent No. 2,464,766. Instead of packing the heat-transferrer with metallic wool, it could be packed with a foraminous carrier impregnated with some non-hygroscopic liquid, such as mineral-oil of the sort referred to in my Patent No. 2,536,081.

The moisture-transferrer shown at 1'5 and the heattransferrer 27 could, as shown in FIG. 1, be substantially similar in construction, or the moisture-transferrer can be constructed as shown at 15a in FIGS. 6 to 11. Therein the moisture-transferrer is shown as being composed, at least as far as its body or core is concerned, of corrugated, treated asbestos paper. The body or core of this moisturetransferrer consists of a spirally-wound layer or strip of the corrugated asbestos paper 37 between the convolutions of which is arranged a flat or uncorrugated divider strip 37a, which latter strip is also composed of treated asbestos paper. As will be clearly seen in FIGS. 10 and 11, this arrangement provides between the corrugations, for a plurality of passages 37b extending axially through the body of the transferrer.

Asbestos as used for the body or core of the moisturetransferrer has numerous and very substantial advantages. It is light in weight and is fireproof.

Another feature found in asbestos which renders it particularly useful as a core or body for a moisture-transferrer, is the fineness of the fibres. While each main fibre of the asbestos paper is visible to the naked eye, the fact remains that each of such fibres is actually composed of a multitude of microscopic fibres, As a result, the asbestos tends to yield more surface within a given volume than, for instance, other fibrous material, such as cellulosic paper. This is of paramount importance in order to bring down the air to be dried to the very lowest relative humidity condition required in order to attain the object of the invention.

Comparative tests made with two wheels of the same thickness, paper weight and flute spacing showed that a wheel composed of the asbestos paper had unexpected advantages as compared to a similar wheel composed of cellulosic paper, which was believed to be the most practical material heretofore. Both wheels were identically impregnated with lithium chloride. The air entering on the drying side had a moisture content of 12 grams per kg. at a temperature of 24 C. The air leaving the cellulosic paper wheel had a moisture content of 5.6 grams at 60 C., while that leaving the asbestos wheel at the same temperature had a moisture content of 3.9 grams. This very substantial difference in drying capacity between asbestos paper and similarly treated cellulosic paper resulted in an increased cooling capacity of an air conditioner in excess of 35%.

This increased efficiency resulting from the use of asbestos paper as compared with cellulosic paper is believed to be due to the following circumstances. Cellulosic fibres have the characteristic of absorbing liquid within the fibres, i.e. the fibres act in the manner of a sponge. In contrast, an asbestos paper can only cover the surface of the fibres. This surface in asbestos paper, however, is extremely large as compared with cellulosic paper. Thus the following phenomenon is believed to take place: at very low relative humidity conditions the liquified hygroscopic salt, such as lithium chloride, becomes very concentrated and thus the percentage of liquid very low. The cellulose fibres absorb and confine this liquid inside the fibres, thus making transfer of moisture to the regenerating air stream difficult. The asbestos fibres, on the other hand, under the same circumstances form a very thin layer of the liquified hygroscopic salt on the outside of the fibres, which layer is in direct contact with the surrounding air.

The heat-transferrer 27 rotates in a casing 28, spanned by bridges 29, with sectoral openings between each face of the casing and the corresponding bridge. The moisturetransferrer 15, although having very similar bridges 30, has a single shroud 31, which projects inwardly from the main container 11, nearly touching the periphery of the rim 16 of the moisture-transferrer. The rim carries two annular pieces of felt 32, one being on each side of, and touching or nearly touching the sides of, the inwardly projecting edge of the shroud.

In FIG. 4 it will be seen that in addition to the partition 33 which separates the two air-passages, there are between the two bridges 30, in extension of the partition, two small plates 34 attached to the two bridges 30, the shroud 31, and the wall 11 of the container, and almost touching the rim 16 of the rotating moisture-transferrer and the two felts 32. These expedients could equally well be substituted in connection with the heat-transferrer. They serve to prevent appreciable leakage of air past the moisturetransferrer, or from passage to passage.

In both types of transferrer, it is desirable to hold the packing in place in some convenient manner, when it is composed of filamentous material, such as aluminum wool, by metal screening secured to each face of the transferrer in any convenient manner, as for example (see FIG. 2) by being cut into sectors 35 inserted between successive ribs 17, and in turn held in place by Wires 36, strung in spider-web formation through transverse holes 370 through the ribs close to the edges thereof. In the embodiment of FIGS. 6-11 such screening is unnecessary.

The incoming air, after having been cooled by the heattransferrer 27, is further cooled by passing it through evaporative pad 38. Water from the tank 39 is sucked through the pipe 40 by electric pump 41, by which this water is impelled through feed pipe 42 to the top of the pad 38, whence it trickles down through this pad, so much of the water as is not evaporated therein, being returned to the tank through the pipe 43.

The tank is supplied with water from any convenient source through supply pipe 46 and ball-cock 47. The air then enters the room or other enclosure through louvres 44.

Exhaust air leaves the room or other enclosure through louvres 45, and is cooled by passing through the evaporative pad 48, which is supplied with water from tank 39 by the pump 49 in the same manner as the pad 38, already described. In place of each of these two pads, there could be used the pads and sprinkler of Patent No. 2,681,217.

Adiabatically cooled by the pad 48, the outgoing air in turn cools the heat-transferrer 27, being itself warmed in the process, and then passes through radiation-shield 50 into chamber 51, where it is joined by the by-passed portion of incoming air entering the chamber through the bypass 23. In this chamber there is an air-heater, which might be an electrically-heated grid of German silver, or any other equivalent heating means; but as shown, is a furnace (preferably gas) 52, which heats the air by means of fins 53 on its flue 54. This furnace, and its flue and fins, are represented here merely conventionally. The furnace or alternative form of air-heater, could be located in an adjoining chamber, with heat exchange means, such as heat-transferrer 27, transferring heat from that chamber to chamber 51.

The outgoing air, greatly heated by the furnace, then passes through the radiation shield 55. Chamber 51 should be lined with some highly heat-reflecting material, backed by heat-insulating material.

The radiation-shield 50 may be of any convenient construction which will shield the heat-transferrer 27 from the direct rays emanating from the air-heater 52, while permitting the free passage of air. The shield should be substantially impervious to heat-radiations, and yet pervious to air. Preferably it should be a stationary pad of substantially the same sort of aluminum wool as employed as a filler for the heat-transferrer 27. The radiation-shield 55 is similar, and similarly protects the moisture-transferrer 15 from the rays of the air-heater 52.

The outgoing air, having been raised in temperature by passing through the heat-transferrer 27 and through radiation-screens 50 and 55, and by the addition of bypassed incoming air, and by air-heater 52, then passes through the moisture-transferrer 15, Where it dries and heats the hygroscopic packing thereof. Thence it is sucked through the centrifugal fan 56 into passage 57, whence it passes outdoors through exit opening 58. In this opening there is provided a butterfly valve 59.

From the passage 57, in the opposite direction there extends a draft passage 60, which connects with the furnace 52 in such a manner as to furnish air-draft thereto. The amount of this draft can be regulated by the butterfly valve 59. Motor 61 drives the shaft 62 through pulley 63, belt 64, and pulley 65. Fans 13 and 56 are keyed to, and driven by, this shaft 62. v

The shaft 62, through gear reduction 66, drives shaft 67 at a very low speed (about 3 r.p.m. or considerably less) and drives shaft 68 at a relatively faster speed (about 25 to 30 r.p.m.). Shafts 67 and 68 enter the speedchanger 69, the details of which are shown enlarged and somewhat symbolically in FIG. 5. In that figure, the slow shaft 67 terminates in a male clutching member 70. Aligned with the shaft 67, there is a driven shaft 71, on which and keyed thereto slides a gear 72 and female clutch member 73 integral with this gear. The fast shaft 68 terminates in a female clutch member 74 and gear 75 integral therewith. Aligned with the shaft 68 there is a driven shaft 76, on which and keyed thereto slides a gear 77 and male clutch member 78 integral with this gear. A fixed dog 79 engages and locks this gear when in its upper position. The driven shaft 71 drives a sleeve 80 which is keyed to the rotary heat-transferrer 27.

The operation and object of the speed-changer just described, is as follows:

Gear 72 and its female clutch member 73, and gear 77 and its male clutch member 78, are raised or lowered simultaneously. When they are both in their lowered position, gears 72 and 75 are disengaged, and both clutches are set. The slow speed of shaft 67 is transmitted through the shaft 71 and sleeve 80 to the moisture-transferrer 15; and the fast speed of shaft 68 is transmitted through shaft 76 and shaft 81 to the heat-transferrer 27.

When they are both in their raised position, the situation shown in FIG. 5, both clutches are released, gear 72 engages gear 75, and gear 77 engages the dog 79. The fast speed of shaft 68 is transmitted through gears 75 and 72 to shaft 71, and thence through sleeve 80 to moisture-transferrer 15; and the engagement of gear 77 with dog 79 locks shaft 76 and thence shaft 81 and the heat-transferrer 27 against rotation. In place of gear 77 and dog 79, any convenient form of brake could be used.

The optimum rotation-speeds differ somewhat for various materials, but can easily be experimentally determined for each. The optimum fast speed for both exchangers is of the order of 25 to 30 r.p.m. The optimum slow speed for a fully-impregnated moisture-exchanger is of the order of 3 r.p.m. or considerably less. For example, for excelsior fully impregnated with triethylene glycol, it is 2 to 3 r.p.m. For excelsior fully impregnated with the best hygroscopic salts, it is /3 to /2 r.p.m. For corrugated asbestos paper impregnated with the best hygroscopic salts, it is of the order of r.p.m., and even less if fully impregnated. Various variables enter into the determination of the optimum slow speed.

At T and T are respectively shown two thermostats, or which can be one double-stage thermostat and H is a humidistat. These devices could be placed at any strategic location in the room or other enclosure which is being air-conditioned, or equivalently in the outgoing airpassage just inside the louvres 45. These three stats control the turning on and off of pumps 41 and 49 and valve V which supplies fuel to the furnace 52.

The humidity-changer consists of the two air-passages, the fans, and the moisture-transferrer 15 in combination with an air-heater 52 to reactivate the hygroscopic packing in the moisture-transferrer, or in further combination with the by-pass 23. But if there still be further added the heat-transferrer 27, and slow rotation be specified for the moisture-transferrer, the resulting sub-combination of the complete air-conditioner, can still be regarded as merely a humidity changer. This arrangement without the addition of further features, has many uses, such as in chemical processes or storage rooms, for which dryness rather than coolness is the predominating consideration. Or it could be employed as a dehumidifying unit for airconditioning, the cooling being supplied in some other manner.

The sub-combination as above defined will now be considered. In FIG. 1, the air in the upper passage passes to the left through the slowly rotating moisture-transferrer 15, after which the non-dehumidified or leastdehumidified portion of the air is carried off through the by-pass 23. This by-passed air carries all or practically all of the sensible-heat which has been transferred into the upper air-stream from the lower air-stream by the moisture-transferrer. The non-by-passed dehumidified air, carrying the heat of condensation resulting from its dehumidification then has practically all of this heat extracted from it by the heat-transferrer 27, and then passes on for whatever use may have been planned for it.

Meanwhile, the air in the lower passage, from whatever source derived, passes in countercurrent, toward the right. It can be here stated that the flow in the lower passage need not necessarily flow opposite to the flow of the dehumidified air above mentioned, as the two flows might well be in the same direction. The air in said lower passage first extracts from the heat-transferrer 27 all the heat which that heat-transferrer extracted from the upper air. Then it is mingled with the hot air from the by-pass 23. Then it is further heated by the air-heater 52. Then its heat, acquired in all of these Ways, is utilized to dry the hygroscopic packing of the moisture-exchanger 15, or 1511, and thus regenerates or reactivates the moistureexchanger.

The apparatus disclosed is one in which most of the sensible heat put into the moisture-transferrer is recaptured by means of the by-pass, and most of the heat of condensation developed by dehumidifying the upper airstream is recaptured by means of the heat-transferrer, and all of this recaptured heat is reused, by preheating the regenerating air-stream, to help reactivate the moisturetransferrer, thus greatly reducing the load on the air heater.

Having thus described embodiments of the invention, it is obvious that the same is not to be restricted thereto, but is broad enough to cover all structures coming within the scope of the annexed claims.

What I claim is:

1. A humidity-changer for air-conditioning, comprising: outgoingair passage means; incoming-air passage means; means for impelling air through the two passage means; a rotary moisture-transferrer mounted for rotating across both passage means; means for rotating the moisture transferrer; and an air heater for heating the outgoing air for regenerating the moisture-transferrer; said humiditychanger being characterized by the fact that the moisturetransferrer comprises a wheel-like casing, and a packing of inert air-permeable absorbent material impregnated with a non-volatile hygroscopic substance, said packing substantially filling said casing, and being held substantially immovable relative to the casing; and by the fact that each level of the packing, when it passes through each passage, is disposed in the same relative position to the other levels of the packing as when it passes through the other passage, and that the air in each passage is impelled through these levels in an order inverse to the passing of the air through these levels in the other passage.

2. A humidity-changer according to claim 1, further characterized by the fact that the means for rotating the moisture-transferrer includes a two-speed change-speed mechanism, whereby the moisture-transferrer can at will be selectively rotated at a very slow speed or at a relatively fast speed.

3. A humidity-changer for air-conditioning, comprising: outgoing-air passage means; incoming-air passage means; means for impelling air through the two passage means; a rotary moisture-transferrer mounted for rotating across both passage means; means for rotating the moisturetransferrer; and an air-heater for heating the outgoing air for regenerating the moisture-transferrer; said humiditychanger being characterized by the fact that the moisturetransferrer comprises a wheel-like casing, and a packing of inert air-permeable liquid-absorbing material capable of being impregnated with a non-volatile hygroscopic liquid, said packing completely filling said casing, and being packed into said casing with such compactness as to remain freely air-permeable and yet to be so self-sustaining as to be substantially immovable with respect to said casing during the rotation of the casing even in a vertical plane; and means secured to the casing at each face thereof to retain the packing therein; and by the fact that each level of the packing, when it passes through each passage, is disposed in the same relative position to the other levels of packing as when it passes through theother passage, and that the air in each passage is impelled through these levels in an order inverse to the passing of the air through these levels in the other passage.

4. A humidity-changer for air-conditioning, comprising: outgoing-air passage means; incoming air-passage means; means for impelling air through the two passage means in countercurrent thermodynamic exchange relationship; a rotary moisture-transferrer mounted for rotating across both passage means; means for rotating the moisturetransferrer; and an air-heater for heating the outgoing air for regenerating the moisture-transferrer; said humiditychanger being characterized by the fact that the incoming-air passage means is divided, at the inward face of the moisture-transferrer, into two branches, across the entrance to one of which successive radii of the rotating moisture-exchanger first pass, and across the entrance to the other of which these radii pass thereafter in their rotation, the first branch leading into the outgoing-air passage means, and the second branch constituting a continuation of the incoming-air passage means, whereby that portion of the air in the incoming-air passage means which is first encountered by successive radii of the rotating moisture-transferrer is by-passed into the outgoing-air stream.

5. A humidity-changer according to claim 4, further characterized by the fact that the first branch of the incoming-air passage means covers sufiicient area of the inward face of the moisture-transferrer so as to receive and by-pass into the outgoing-air passage means substantially so much of the incoming air as is not dehumidified by the moisture-transferrer.

6. A humidity-changer according to claim 4, characterized by the fact that the first branch of the divided incoming-air passage means leads into the outgoing-air passage means upstream from the heater.

7. A humidity-changer according to claim 4, characterized by the fact that there is in the first branch a valve which can be set at will selectively to open the first branch to the outgoing-air passage or to close it therefrom.

8. A humidity-changer according to claim 7, further characterized by the fact that the means for rotating the moisture-transferrer includes a two-speed change-speed mechanism, whereby the moisture-transferrer can at will be selectively rotated at a very slow speed or at a relatively fast speed.

9. A humidity-changer according to claim 4, characterized by the fact of having in the first branch means which can be set at will selectively to open the first branch to the outgoing-air passage and close it to a continuation of the incoming-air passage, or vice versa.

10. A humidity-changer according to claim 4, further characterized by the fact that the means for rotating the moisture-transferrer includes a two-speed change-speed mechanism, whereby the moisture-transferrer can at will be selectively rotated at a very slow speed or at a relatively fast speed.

11. A humidity-changer for air-conditioning, comprising; outgoing-air passage means; incoming-air passage means; means for impelling air through the two passage means in countercurrent thermodynamic exchange relationship; a moisture-transferrer comprising an hygroscopic air-permeable mass mounted to move cyclically across both passage means, means for so moving the moisture-transferrer, said means including a two-speed speedchanger, by which the moisture-transferrer can at will be selectively moved at a very slow speed or at a relatively fast speed; whereby the moisture-transferrer can at will selectively transfer moisture from the cooler air stream to the hotter air stream regardless of difierences in moisture content, or transfer moisture from the more moist stream to the less moist stream regardless of difierences in temperature.

12. A humidity-changer for air-conditioning, comprising; out-going air-passage means; incoming-air passage means, means for impelling air through the two passages in countercurrent thermodynamic exchange relationship; a rotary wheel-like casing, said casing being mounted for rotating across both passage means; means for rotating the casing, said means including a two-speed speedchanger by which the casing can at will be selectively rotated at a very slow speed or at a relatively fast speed; and in the casing, a packing of non-volatile air-permeable material of such characteristics that, when the casing is rotated at the low speed, the packing will transfer moisture from the cooler air-stream to the hotter air-stream regardless of dilferences in moisture content, and when the casing is rotated at the high speed, the packing will transfer moisture from the more moist stream to the less moist stream regardless of differences in temperature.

13. A humidity-changer according to claim 12, further characterized by the fact that the very slow speed is of the order of less than 3 r.p.m., and that the relatively fast speed is of the order of 25 to 30 r.p.m.

14. A humidity-changer for air-conditioning, comprising; two air-passages; means for impelling a stream of air through each of said passages; a mass of inert airpermeable liquid-absorbing material impregnated with a hygroscopic liquid; means for bodily moving this mass cyclically across said passages; and means for heating the air in one passage to regenerate said mass; characterized by the fact that each level of the mass is disposed in each passage in the same relative position to the other levels as in the other passage, and that the air in each passage is impelled through these levels in an inverse order to the passing of the air through these levels in the other passage.

15. A humidity-changer comprising; two air-passages; means for impelling air through said passages in countercurrent thermodynamic exchange relationship; a moisturetransferrer mounted to move cyclically across said passages; a heat-transferrer, mounted to move cyclically across said passages, an air-heater for regenerating the moisture-transferrer located between the heat-transferrer and the moisture-transferrer, in that in one of the two passages the air is directed in said passage toward the moisture-transferrer; and means for moving both transferrets.

16. A humidity-changer according to claim 15, characterized by having, between the heat-transferrer and the air-heater, an air-pervious screen relatively impervious to heat-radiations.

17. A humidity-changer according to claim 15, further characterized by the fact that one of said passages in which the air flows from the moisture-transferrer toward the heat-transferrer, is divided at the face of the moisturetransferrer nearest to the heat-transferrer, into two branches; that across the entrance to one of said branches successive portions of the moisture-transferrer first pass cyclically; that across the entrance to the other of said branches these portions pass thereafter in their cyclic motion; that the first branch leads into the other passage upstream from the moisture-transferrer; and that the second branch constitutes a continuation of the first passage; whereby the part of the air in the first passage which is first encountered by successive portions of the moisturetransferrer in its cyclic motion, and thus is the hottest and least dehumidified, is by-passed into the air in the second passage at a point where its heat can be re-used to help regenerate the moisture-transferrer.

18. A humidity-changer comprising: two air-passages; means for impelling air through the passages in countercurrent thermodynamic exchange relationship; a moisture-transferrer, mounted to move cyclically across said passages; means for so moving said moisture-transferrer; an air heater located in one of the two passages for regenerating the moisture-transferrer; an air pervious screen relatively impervious to heat radiations, located in that passage between the air-heater and the moisturetransferrer.

19. Apparatus for drying air for use in an enclosure, comprising, a first air-passage, for conveying air to the enclosure; a second air-passage; means for impe'lling two streams of air in countercurrent flow through the respective passages; means for dehumidifying and heating the air in the first passage by heat-and-moisture exchange with the air in the second passage, this heating being to some extent accomplished by transfer of sensible heat from the air in the second passage to the air in the first passage, but principally by conversion of latent heat of the air in the first passage into sensible heat by condensation of moisture in the air in the first passage; means for then substantially anhydrously extracting heat from the air in the first passage by heat-exchange with the air in the second passage, thereby heating the air in the second passage; and means for then further anhydrously heating the air in the second passage; these last two heatings of the air in the second passage occurring upstream in said passage from the heat-and-moisture exchange means; whereby the air in the first passage is dried, and the major portion of the heat of condensation resulting from such drying is extracted from the air in the first passage, and is transferred to the air in the second passage by the above-mentioned anhydrous heat-exchange means, to be used to help regenerate the heat-and-moisture exchange means.

20. Apparatus according to claim 19, wherein there is a by-pass, extending from between the heat-and-moisture exchange means and the anhydrous heat-exchange means in the first passage, to between the anhydrous heatexchange means and the air-heater means in the second passage, for extracting from the air in the first passage so much of said air as has not be dehumidified by the heatand-moisture exchange means, and for dumping such extracted air into the second passage.

21. Apparatus according to claim 20, wherein the first passage leads from outdoors, and the second passage leads from the enclosure.

22. A humidity-changer for air conditioning comprising: an incoming-air passage; a second air-passage; means for irnpelling a stream of air through said passages; a rotary moisture-transferrer mounted for rotating across both passages; means for rotating the moisture-transferrer, said means including a two-speed change-speed mechanism, whereby the moisture-transferrer can at will be selectively rotated at a very slow speed or at a relatively fast speed, and an air heater for heating the air in the second passage for regenerating the moisture-transferrer; said humidity-changer being further characterized by the fact that the moisture-transferrer comprises a wheel-like casing and a packing of inert air-permeable liquid-absorbing material impregnated with a non-volatile hygroscopic substance, said packing substantially filling said casing, and being held substantially immovable relatively to said casing.

23. A humidity-changer for air-conditioning, comprising, two air-passages; means for impelling a stream of air through each of said passages; 21 mass of inert airpermeable liquid-absorbing material, impregnated with an hygroscopic liquid; means for bodily moving this mass cyclically across said passages, said last-mentioned means including a two-speed change-speed mechanism whereby the mass can at will be selectively moved at a very slow speed or at relatively fast speed; and means for heating the air in one passage to regenerate said mass.

References Cited UNITED STATES PATENTS 1,482,626 2/ 1924 Whiting.

2,200,243 5/1940 Newton et a1. 62-176 2,264,221 11/1941 Smith 7 2,286,480 6/1942 Farr 261-92 OTHER REFERENCES Hackhs Chemical Dictionary, 3rd. edition, McGraw- Hill N.Y., 1944, C. 122 (pp. 78 and 79 relied on).

HARRY B. THORNTON, Primary Examiner. TIM R. MILES, Assistant Examiner. 

1. A HUMUDITY-CHANGER FOR AIR-CONDITIONING, COMPRISING: OUTGOING-AIR PASSAGE MEANS; INCOMING-AIR PASSAGE MEANS; MEANS FOR IMPELLING AIR THROUGH THE TWO PASSAGE MEANS; A ROTART MOISTURE-TRANSFERRER MOUNTED FOR ROTATING ACROSS BOTH PASSAGE MEANS; MEANS FOR ROTATING THE MOISTURE TRANSFERRER; AND AN AIR HEATING THE OUTGOING AIR FOR REGENERATING THE MOISTURE-TRANSFERRER; SAID HUMIDITYCHANGER BEING CHARACTERIZED BY THE FACT THAT THE MOISTURETRANSFERRER COMPRISES A WHEEL-LIKE CASING, AND A PACKING OF INERT AIR-PERMEABLE ABSORBENT MATERIAL IMPREGNATED WITH A NON-VOLATILE HYGROSOPIC SUBSTANCE, SAID PACKING 